Portable electronic devices such as laptop and notebook computers are too large to be worn or carried continuously, yet are readily stolen when momentarily unattended. Accordingly, specialized locking mechanisms have been developed to prevent theft without impairing convenience of use. These frequently involve engagement with a standardized, dedicated locking port or aperture within the body of the equipment. The locking aperture is so located that the equipment may still be operated when secured.
A typical locking arrangement includes a lock and a flexible but sturdy cable emerging from the lock. The cable, which may terminate in a loop, is drawn around a convenient stationary fixture. The lock is passed through the cable loop and then secured to the equipment through the locking port.
For example, U.S. Pat. No. 5,327,752 describes a tubular lock with a key-operated, rotable T-shaped spindle that emerges from an end face of the lock body. The spindle is inserted into the locking port of an item to be protected; the locking port is asymmetric with dimensions slightly larger than those of the spindle head. After the spindle head clears the interior surface of the wall, it may be rotated, using a properly fitting key inserted in the opposite face of the lock. A 90.degree. rotation secures the spindle head behind the interior wall surface.
To prevent the lock from simply being rotated and the spindle removed from the locking port, the tubular lock of the '752 patent contains two additional features. First, a pair of "anti-rotation arms" flanking the spindle are inserted, along with the spindle, into the locking port; forming an off-round configuration, the spindle neck and the flanking arms cannot be rotated within the asymmetric port. Second, the entire lock is urged against the exterior surface of the article to be secured by a spring mechanism. As the spindle and arms are passed through the locking port, the lock is pressed against the article to be secured and the key used to rotate the spindle head into the locked position. The lock is then released, the spring mechanism keeping it biased against the article surface.
This type of lock is disadvantageous both in requiring a spring bias, which reduces the convenience of use while increasing the cost of manufacture, and in the need for an asymmetric locking port.